Download 10562_2008_9826_MOESM1_ESM

Supporting information
A non-sodium synthesis of highly ordered V-MCM-41 and its catalytic
application in isomerization
Shuangquan Hu1, Dapeng Liu1, Lusi Li1, Armando Borgna2, Yanhui Yang1*
1
School of Chemical and Biomedical Engineering, Nanyang Technological
University, Singapore, 637459
2
Institute of Chemical Engineering and Sciences, Singapore, 1 Pesek Road, Jurong
Island, 627833, Singapore
* To whom correspondence should be addressed.
Email address: [email protected]
Tel: +65 6316 8940, Fax: +65 6794 7553
1
Scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM)
The particle size and morphology of 1V-MCM-41 samples determined by SEM
image are shown in Figure S1. The SEM image shows that the V-MCM-41 particles
are spherically shaped with particle size of 400 nm. The small size may bring good
catalytic performance due to its accessibility of the active site. TEM image of
1V-MCM-41 is also shown in Figure S1, from which well-ordered arrays of
mesopores was observed. The space between each channel is about 4 nm, and it is in
good agreement with the test results of XRD and N2 physisorption.
Figure S1. SEM and TEM images of 1V-MCM-41
FT-IR
FT-IR spectra of V-MCM-41 samples are depicted in Figure S2. The broad band
at around 3500 cm-1 is attributed to the adsorption of surface moisture. The absorption
bands at 1620-1640 cm-1 arising from bending vibration of adsorbed water molecules
confirm the presence of water molecules physically adsorbed on the samples. The
band observed at 802 cm-1 is the symmetric stretching vibrations of the Si-O-Si
groups and the sharp band at 1085 cm-1 is the asymmetric stretching of the Si-O-Si
2
vibrations. The peak observed around 960 cm-1 is generally attributed to stretching
vibration of SiO4 units bonded to a transition metal cations or Si-O stretching
vibration of Si-O∙∙∙H. The shift of 1085 cm-1 peak after vanadium substitution may
indicate the vanadium is in the framework of MCM-41. Furthermore, no peaks are
found in the range 830-850 cm-1 which is assigned for V-O-V crystalline band of
V2O5 moieties. This suggests there is no vanadyl polymers formed in these
V-MCM-41 samples.
Figure S2. FT-IR spectra of Si-MCM-41, 1V-MCM-41, 2V-MCM-41 and
3V-MCM-41
Hydrogen temperature programmed reduction (H2-TPR)
By H2-TPR analysis, not only the reducibility and stability of the metal supported
or unsupported catalysts can be revealed, but also the more profound surface chemical
information, i.e., metal species, metal distribution, the loading of different metal
surface forms, can be ideally provided. In this study, the temperature programmed
3
reduction was carried out from 323K to 1073K for 1V-MCM-41, 2V-MCM-41,
3V-MCM-41 as well as the impregnated V/MCM-41.
The H2-TPR profiles are shown in Figure S3. The strong reduction peak at around
778K is attributed to the reduction of vanadium in the framework. Only one sharp
reduction signal for 1V-MCM-41, 2V-MCM-41, 3V-MCM-41 indicates the uniform
distribution of vanadium species with single valence state, the valence state changes
from V5+ to V3+ after reduction calculated by the hydrogen consumption. For the
vanadium impregnated sample V/MCM-41, there is a board peak around 607K due to
the presence of the vanadium on the surface of MCM-41 in which there is a lack of
strong interaction with MCM-41 support.
Figure S3. H2-TPR profiles of impregnated vanadium on different catalysts.
(a),(b),(c),(d) represent impregnated V/MCM-41, 1V-MCM-41, 2V-MCM-41,
3V-MCM-41
4
Structure stability after reaction
N2 physisorption and XRD experiments were performed to test the structural
stability of V-MCM-41 catalysts under reaction conditions, as shown in Figure S4.
The XRD patterns illustrate that the V-MCM-41 sample still preserves its good
hexagonal structure even under reaction conditions. Nitrogen physisorption was also
tested as shown in Figure S4 (b) and (c); it confirms the XRD results that our
V-MCM-41 samples are stable under this isomerization reaction conditions.
Figure S4. (a) XRD patterns of 1V-MCM-41 before and after reaction of heptene
isomerization.
(b) Isotherm graph of 1V-MCM-41 before and after heptene
isomerization reaction (c) pore size distribution of 1V-MCM-41 before and after
heptene isomerization reaction. A represents the sample before reaction and B
represents the sample after reaction.
5